The long range goal of this proposal is an understanding of prolactin action on the ovaries of higher mammals. To achieve this goal, we will study the biological effects of prolactin on porcine ovarian cells in vitro. Our studies have shown definite luteotrophic effects of prolactin on these cells which will now be characterized. The sensitivity of these cells appears to depend on critical maturational events which can be observed in vitro. To understand the requirements for prolactin responsiveness, we will investigate the hormonal control and cell biology of prolactin receptor function. These studies have already demonstrated steroid hormone modulation of receptor activity. We now hope to understand these events in terms of receptor translocation and receptor synthesis. In addition, we will study the hormonal control of ornithine decarboxylase and polyamines in these cells which may be regarded as potential mediators or modulators of the actions of prolactin and other hormones.